very little information is available to evaluate myclobutanil in the context of tobacco use, as Eagle 20 and myclobutanil-based fungicides are not approved for use on tobacco plants in the United States (6,7). Myclobutanil is approved for use on tobacco cultivated in China, however, and a 2012 study has demonstrated that 10% or more of the active pesticide remains on tobacco leaves up to 21 days after treatment, with residue present from 0.85 parts per million (ppm) up to 3.27 ppm (8). Using tobacco as a model for pesticide retention, it is probable a considerable amount of myclobutanil may remain present in cannabis weeks after fungicide application.
Of the three primary decomposition products formed, HCN holds the greatest concern. Chronic exposure to dilute hydrogen cyanide (ex. 0.008 parts per million) is not immediately deadly (10), but is known to cause serious neurological, respiratory, cardiovascular, and thyroid problems (11, 12, 13). Cannabis retaining even marginal amounts of myclobutanil (ex. 0.03 ppm) could potentially expose consumers to non-lethal, but clinically relevant levels of HCN.
III. Myclobutanil is co-extracted with cannabinoids during concentrate production
Studies of two other conazole fungicides, tebuconazole and propiconazole, have demonstrated that these chemicals are co-extracted during production of essential oils (14). Moreover, the process of extraction, treatment, and concentration can cause tebuconazole and propiconazole pesticide residue to accumulate at levels 250 times higher than the starting material (14). Myclobutanil is highly soluble in many of the solvents used in cannabinoid extraction (ex. ethanol, butane, and carbon dioxide)(15,16), and unquestionably co-extracts with cannabinoids during concentrate production. The process of removing residual solvent and increasing cannabinoid concentration very likely increases levels of myclobutanil, and other chemically-similar pesticides
6. "Myclobutanil; Pesticide Tolerance. a Rule by the Environmental Protection Agency on 03/26/2008." Federal Register. National Archives And Records Administration, 3 Mar. 2008. Web. 5 May 2015. <https://www.federalregister.gov/articles/2008/03/26/E8-6205/myclobutanil-pesticide-tolerance>.
7. Daley, Paul, David Lampach, Savino Sguerra, and BOTEC Analysis Corporation. "Testing Cannabis for Contaminants." Washington State Liquor Control Board. Washington State, 12 Sept. 2013. Web. 5 May 2015. <http://liq.wa.gov/publications/Marijuana/BOTEC%20reports/1a-Testing-for-Contaminants-Final-Revised.pdf>.
8. Pfeufer, Emily, and Bob Pearce. "2015 Fungicide Guide for Burley and Dark Tobacco." College Of Agriculture, Food And Environment. University Of Kentucky, Jan. 2015. Web. 5 May 2015. <http://www2.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/ppfsagt8.pdf>.
11. "Cyanide Compounds." Air Toxics. U.S. Environmental Protection Agency, Jan. 2000. Web. 5 May 2015. <http://www.epa.gov/ttnatw01/hlthef/cyanide.html>.
12. El Ghawabi, SH, MA Gaafar, AA El-Saharti, SH Ahmed, KK Malash, and R Fares. "Chronic Cyanide Exposure: a Clinical, Radioisotope, and Laboratory Study." British Journal of Industrial Medicine 32(1975): 215-219. Web. 5 May 2015.
13. "Toxicological Profile for Cyanide." Agency For Toxic Substances & Disease Registry. U.S. Department Of Health And Human Services, July 2006. Web. 5 May 2015. <http://www.atsdr.cdc.gov/toxprofiles/tp8.pdf>.
14. Blanc, P, M Hogan, K Mallin, D Hryhorczuk, S Hessl, and B Bernard. "Cyanide Intoxication Among Silver-reclaiming Workers." The Journal of the American Medical Association 253(1985): 367-371. Web. 5 May 2015.
15. Tascone, O, C Roy, JJ Filippi, and UJ Meierhenrich. "Use, Analysis, and Regulation of Pesticides in Natural Extracts, Essential Oils, Concretes, and Absolutes." Analytical and Bioanalytical Chemistry 406(2014): 971-980. Web. 5 May 2015.
16. Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium, 11 th ed., British Crop Protection Council, Surrey, England 1997, p. 854
Of the three primary decomposition products formed, HCN holds the greatest concern. Chronic exposure to dilute hydrogen cyanide (ex. 0.008 parts per million) is not immediately deadly (10), but is known to cause serious neurological, respiratory, cardiovascular, and thyroid problems (11, 12, 13). Cannabis retaining even marginal amounts of myclobutanil (ex. 0.03 ppm) could potentially expose consumers to non-lethal, but clinically relevant levels of HCN.
III. Myclobutanil is co-extracted with cannabinoids during concentrate production
Studies of two other conazole fungicides, tebuconazole and propiconazole, have demonstrated that these chemicals are co-extracted during production of essential oils (14). Moreover, the process of extraction, treatment, and concentration can cause tebuconazole and propiconazole pesticide residue to accumulate at levels 250 times higher than the starting material (14). Myclobutanil is highly soluble in many of the solvents used in cannabinoid extraction (ex. ethanol, butane, and carbon dioxide)(15,16), and unquestionably co-extracts with cannabinoids during concentrate production. The process of removing residual solvent and increasing cannabinoid concentration very likely increases levels of myclobutanil, and other chemically-similar pesticides
6. "Myclobutanil; Pesticide Tolerance. a Rule by the Environmental Protection Agency on 03/26/2008." Federal Register. National Archives And Records Administration, 3 Mar. 2008. Web. 5 May 2015. <https://www.federalregister.gov/articles/2008/03/26/E8-6205/myclobutanil-pesticide-tolerance>.
7. Daley, Paul, David Lampach, Savino Sguerra, and BOTEC Analysis Corporation. "Testing Cannabis for Contaminants." Washington State Liquor Control Board. Washington State, 12 Sept. 2013. Web. 5 May 2015. <http://liq.wa.gov/publications/Marijuana/BOTEC%20reports/1a-Testing-for-Contaminants-Final-Revised.pdf>.
8. Pfeufer, Emily, and Bob Pearce. "2015 Fungicide Guide for Burley and Dark Tobacco." College Of Agriculture, Food And Environment. University Of Kentucky, Jan. 2015. Web. 5 May 2015. <http://www2.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/ppfsagt8.pdf>.
11. "Cyanide Compounds." Air Toxics. U.S. Environmental Protection Agency, Jan. 2000. Web. 5 May 2015. <http://www.epa.gov/ttnatw01/hlthef/cyanide.html>.
12. El Ghawabi, SH, MA Gaafar, AA El-Saharti, SH Ahmed, KK Malash, and R Fares. "Chronic Cyanide Exposure: a Clinical, Radioisotope, and Laboratory Study." British Journal of Industrial Medicine 32(1975): 215-219. Web. 5 May 2015.
13. "Toxicological Profile for Cyanide." Agency For Toxic Substances & Disease Registry. U.S. Department Of Health And Human Services, July 2006. Web. 5 May 2015. <http://www.atsdr.cdc.gov/toxprofiles/tp8.pdf>.
14. Blanc, P, M Hogan, K Mallin, D Hryhorczuk, S Hessl, and B Bernard. "Cyanide Intoxication Among Silver-reclaiming Workers." The Journal of the American Medical Association 253(1985): 367-371. Web. 5 May 2015.
15. Tascone, O, C Roy, JJ Filippi, and UJ Meierhenrich. "Use, Analysis, and Regulation of Pesticides in Natural Extracts, Essential Oils, Concretes, and Absolutes." Analytical and Bioanalytical Chemistry 406(2014): 971-980. Web. 5 May 2015.
16. Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium, 11 th ed., British Crop Protection Council, Surrey, England 1997, p. 854
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